fern

Introduction

fern, any plant of the division Polypodiophyta. Fern species, numbering several thousand, are found throughout the world but are especially abundant in tropical rain forests. The ferns and their relatives (e.g., the club moss and horsetail) are the most primitive plants to have developed a true vascular system (see plant). The asparagus fern and shrub sweet fern (see bayberry) of florists are not true ferns.